Various designs of furniture for supporting one or more persons, typically in either a seated or reclining position, and, additionally, for providing some motion relative to the ground or floor of an assembly that supports the person, are known in the art. Such furniture, as broadly described, includes such common items as rocking chairs and gliders. Additional devices that are fixed in position and both support a person and that provide for motion of the person fall into the category of juvenile products or physical exercise equipment. In some cases, motion of the supporting assembly is relative to a base component of the furniture item, where the base component is supported by the floor or ground. In the present description and in any appended claims, the term "floor" will be used to encompass any surface upon which an item of furniture may rest, and may include, without limitation, the ground.
One means known for providing for motion of a support assembly relative to a base of an item of furniture utilizes linkage assemblies which produce an arc-like path and was previously discussed in U.S. Pat. No. 5,618,016 (the "'016 patent"), which patent is incorporated herein by reference.
Furniture items, such as those surveyed in the foregoing paragraphs, that provide for motion of one or more supported persons, typically require either:
(1) that a force be exerted on the supporting assembly with respect to a surface external to the furniture; or PA1 (2) that an occupant displace his center of gravity substantially to cause or sustain oscillatory motion. PA1 a. providing an apparatus that has a support, an oscillatory mechanism that defines a path of motion with a region bilaterally symmetrical with respect to a reference point, and an actuator permitting the subject, while supported by the support, to control the oscillatory mechanism; and
Thus, for example, an ordinary rocking chair is driven by action of the feet of the occupant against the floor, or, in some cases, against an ottoman. In order to maintain a continuous motion such as an oscillatory rocking, the occupant's feet must either be kept on the floor or periodically placed there to drive the motion. In a common suspended swing or its variants, the occupant must exert enough force to substantially shift his center of gravity with respect to the equilibrium point of the motion. In either case, braking the motion of the support similarly requires exertion of a force with respect to a stationary surface or substantial motion of the center of gravity of the occupant.